Even with the proven accuracy of DNA testing, it is possible -- though improbable -- that the results are incorrect. Some of the grounds for challenging a paternity determination include:

• Tainted lab results (e.g., evidence of prior errors in lab results and routinely substandard work)
• Fraudulent lab results (e.g., evidence that the opposing party sent someone else to take the lab test on his behalf)
• Proof of infertility/sterility
• Proof that test results were tampered with